The online microwave moisture tester, with its non-contact and real-time monitoring technology advantages, is widely used in fields such as food processing, agriculture, and building materials, and has become a key equipment for controlling the moisture content of materials in industrial production. This article will analyze its core mechanism and maintenance points from two dimensions: technical principles and daily maintenance.

1、 Technical principle: The underlying logic of penetrating microwave detection

The core technology of online microwave moisture tester is based onPrinciple of high-frequency capacitive wave penetrationBy analyzing the difference in dielectric constant of materials to achieve moisture measurement, the workflow can be divided into three key steps:

1. Microwave transmission and signal reception

The instrument is equipped with a built-in microwave generator, which emits high-frequency electromagnetic waves (usually2.45GHzor5.8GHz）. When microwaves penetrate materials, their energy is absorbed by polar molecules (such as water molecules) in the material and converted into thermal energy, resulting in microwave signal attenuation. The receiver calculates the attenuation by capturing the strength of the microwave signal after penetration.

2. Correlation between dielectric constant and moisture content

The dielectric constant of different materials varies significantly: the dielectric constant of water（A380）Far higher than gravel（A3-4）Dry powder（A3-10）Waiting for dry materials. When the moisture content of the material increases, its overall dielectric constant approaches the value of water. The instrument measures the change in dielectric constant of the penetrating material through a sensor probe, and combines it with a preset algorithm model to convert the dielectric constant into a percentage of moisture（0-100%Quality ratio). For example, in grain processing, if the probe measures the dielectric constant of the material as30It can be inferred that its moisture content is approximately15%.

3. Penetrating measurement and depth control

The sensor probe adopts high-frequency capacitance technology, which can penetrate materials150-200mmThickness, directly measure the total amount of core moisture and surface moisture. The advantage of this technology lies in:

Anti surface interference: Surface contaminants, dust, or oxide layers on materials will not affect measurement results, making it suitable for complex scenarios such as conveyor belts and silos.

Full section inspection: The penetration depth can cover the inside of the material pile, avoiding errors caused by only detecting surface moisture. For example, in a coal yard, it is possible to accurately identify the damp areas inside and prevent the risk of spontaneous combustion.

4. Temperature compensation and signal correction

The temperature of the material can affect the measurement results of the dielectric constant (an increase in temperature leads to intensified molecular thermal motion and a decrease in dielectric constant). Built in instrumentPT100Temperature sensor, real-time monitoring of material temperature (range)-10℃to90℃）And automatically adjust the moisture calculation value through algorithms to ensure data accuracy.

2、 Daily maintenance: key points to ensure the long-term operation of equipment

To ensure the measurement accuracy and stability of the online microwave moisture tester, daily maintenance needs to be implemented from three aspects: cleaning, calibration, and environmental control:

1. Probe cleaning and anti blocking

Regular dust removal: Use a soft bristled brush to clean the dust or material residue attached to the surface of the probe every week to prevent signal attenuation.

Anti adhesion treatment: When detecting highly viscous materials such as syrup and wet mud, an anti adhesion coating (such as polytetrafluoroethylene) can be applied to the contact surface of the probe to reduce residue.

Avoid mechanical damage: Do not use hard tools to scrape the probe during cleaning to prevent damage to the wear-resistant ceramic or zirconia coating.

2. Regular calibration and accuracy verification

Standard sample calibration: Use standard samples with known moisture content (such as dry weights, standard humidity blocks) for calibration every quarter to ensure measurement error≤±0.1%.

Comparative verification: Compare the instrument data with the laboratory drying method results every month. If the deviation exceeds the allowable range, recalibration or contact the manufacturer for maintenance is required.

3. Environmental adaptability management

Temperature control: Avoid prolonged exposure of the instrument to high temperatures (>60℃）Or low temperature (＜-10℃）Prevent the performance degradation of electronic components in the environment.

Moisture and corrosion prevention: In humid or corrosive environments (such as chemical workshops), protective covers should be installed and probe sealing should be checked regularly.

Electromagnetic interference isolation: Keep away from strong electromagnetic sources (such as large motors and frequency converters) to prevent signal interference from causing data fluctuations.

4. Electrical system inspection

Power stability: Ensure the supply voltage（24VDC±10%）Stability, avoiding circuit damage caused by overvoltage or polarity reversal.

Signal line maintenance: Check the output signal line monthly (such asRS485The4-20mA）Check if the connection is loose to prevent data interruption caused by poor contact.

Conclusion

The online microwave moisture tester achieves real-time and accurate measurement of material moisture through penetrating microwave detection technology, and scientific daily maintenance is the key to ensuring its long-term stable operation. Enterprises can reduce equipment failure rates by establishing standardized maintenance processes such as daily cleaning, weekly calibration, and monthly in-depth inspections60%Above, while extending the lifespan of the probe to3-5Ultimately achieving a dual improvement in production efficiency and product quality.